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Set up two simultaneous equations and solve these. Be sure to use all of the information provided.

This problem will require the confident use of differentiation of logarithms and the chain rule.

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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